Canada opened their title defence by downing Italy as Great Britain upset Australia on the second day of Davis Cup final group stage action on Wednesday. The Czech Republic won their tie against a Spain side sorely missing world number two Carlos Alcaraz, while US Open men's doubles champion Rajeev Ram helped the United States team battle past Croatia.
The top two from each of the 16-team four group round robin will move into the knockout phase in Spain in November.
Canada stayed on course for the grand finale in Malaga next month courtesy of straight set wins in the opening singles by Alexis Galarneau and then Gabriel Diallo.
Galarneau and Vasek Pospisil then claimed a tense 6-7 (4/7), 6-4, 7-6 (7/3) win over Matteo Arnaldi and Simone Bolelli to defeat the Italians 3-0 in Bologna.
Last year's runners-up Australia took the doubles to leave the home side 2-1 winners, with the 2015 champions second to France, who beat Switzerland 24 hours earlier, in Group B.
The United States had to dig deep in Split to overcome hosts Croatia 2-1. Mackenzie McDonald got the record 32-time winners off to a positive start with a 6-4, 6-2 win over 18-year-old Dino Prizmic.
Borna Gojo then levelled the tie by toppling US Open quarter-finalist Frances Tiafoe (USA) 6-4, 7-6 (8/6).
That left everything resting on the fate of the closing doubles, with Ram, fresh from his third straight title at Flushing Meadows, linking up with Austin Krajicek to see off Ivan Dodig and Mate Pavic 7-6 (7/5), 6-7 (3/7), 6-2.